1. Field of the Invention
The present invention relates to a horizontal AFC (automatic frequency control) circuit employed in a TV (television) receiver.
2. Description of the Prior Art
There are possibilities that horizontal synchronization of a TV receiver is disturbed due to noise mixed into a picture (video) signal and a jitter occurring in a picture signal derived from a VTR and the like. Accordingly, in general, an automatic frequency control (AFC) is performed by a horizontal AFC circuit with respect to a horizontal synchronizing (sync) signal.
In the above-described conventional horizontal AFC circuit, both of the flow-up performance of the horizontal AFC circuit and the performance capable of eliminating adverse influences caused by the noise (antinoise characteristic) thereof can be hardly satisfied at the same time. A proper compromise should be made between these characteristics. As a consequence, the horizontal AFC circuit may not follow up the jitter caused by the VTR and the like, but also the TV picture may be scratched due to the noise.